Shipping container

ABSTRACT

An improved shipping container for a book or the like having an improved end cell cushioning structure which is formed from cushioning panels attached to the bottom panel of the container and adapted to be folded into a square or rectangular cellular cushion. Additionally, the cushioning panels include triangular panels which are folded inwardly to provide rigidity to the cellular cushion. The new and improved shipping container is formed out of a single piece of paperboard having a minimal size and, due to its unique construction, it may be easily formed around the book or similar object to be packaged within the container on book folding machines of the type well known in the art.

United States Patent [191 Sieffert June 28, 1974 SHIPPING CONTAINERPrimary Examiner-William I. Price r- Assistant Eraniiner Bruce H.Bernstein [75] Inventor. illiam G. Siefiert, Jollet, Ill. Attorney g orFirm DOrsey L Baker [73] Assignee: Olinkraft, Inc., West Monroe, La. 22Filed: July 16, 1973 [57] ABSTRACT An improved shipping container for abook or the like [21] Appl- 3795 having an improved end cell cushioningstructure which is formed from cushioning panels attached to [52] US. Cl229/40, 206/424, 206/52], the bottom panel of the Container and adaptedto be 229/34 w folded into a square or rectangular cellular cushion. 51] Int. Cl 865d 5/02, 865d 85/30 Additionally, the cushioning Panelsinclude triangular [58 Field of Search 206/46 FR, 45.26; 229/33, panelswhieh are folded inwardly to Provide rigidity to 229 34 w 40 39 B thecellular cushion. The new and improved shipping container is formed outof a single piece of paper- 5 References Cited board having a minimalsize and, due to its unique UNITED STATES PATENTS construction, it maybe easily formed around the book or similar object to be packaged withinthe container 32:2 53/32 on book folding machines of the type well knownin 31734397 5/1973 Cote 229/39 B the 14 Claims, 6 Drawing FiguresPATENTEDJUN28 1974 3320.709

sum 1 0F 2 FIG! 42 HIHHH PMENTEDmza m4 SHEET 2 [1F 2 I l l I 1 SHIPPINGCONTAINER BACKGROUND OF THE INVENTION This invention relates to ashipping container and more particularly to a mailing container forprotecting a book or the like with the container having a unique endcell construction which cushions the ends of the book or other objectfrom damage that often occurs during the mailing of the container.

Mailing container structures have previously included cushioning endcells for the purpose of protect ing the ends of a book which ispackaged in the con tainer from the damaging shocks which seem to occuroften during delivery of the package through our postal system. Such endcells have taken many forms, one of which is typified by the US. Pat.No. 2,847,152, issued to L. D. Van Antwerpen on Aug. 12, 1958 whereinthe end panel construction is formed as a wrap-around hollow memberformed out of five panels which are folded out of the flap shown as thenumeral 9 in FIG. 2 of the drawing. A variation of this concept is shownin the US. Pat. No. 3,179,325, issued to R. H. Johnson on Apr. 20, 1965wherein the cushioning end cell is formed of three intermediate stripsor panels numbered 50, 52, 54 and 32, 34 and 36 as shown in FIG. 4 ofhis drawing. A more refined variation of this type end cell constructionis shown in the US. Pat. No. 3,368,735, issued to H. L. Levi on Feb. 13,1968 wherein four panels numbered P6, P7 P8 and P9 are utilized incombination with a tab labeled T2 as shown in FIG. 1 of his drawing.

Another variationof this type of end cell construction is shown in theUS Pat. No. 3,386,641, issued to 13. Cassidy on June 4, 1968 whereinfour panels numbered 40, 41, 42 and 43 are utilized in combination withother panels to provide a wrap-around end cell construction forcushioning the book in the package. Other designs of end cells wereattempted as typified by the US. Pat. No. 3,386,642, issued to G. H.Young on June 4, 1968 wherein a six panel structure was attempted usingthe panels numbered 8, 34, 26, 42, 27 and 35 as shown in FIG. 1 of hisdrawing which were folded in the manner shown in FIG. 2 of the drawingto provide the end cell construction. As a variation of this type ofstructure reference should be made to the US. Pat. No. 3,399,821, issuedto N. A. Ringholz on Sept. 3, 1968 wherein a four panel constructionutilizing panels numbered 25, 26 and 27 were folded to form the end cellcushioning structure shown in FIG. 2 of his drawing. A more simplifiedversion of this structure is also shown in the US. Pat. No. 3,485,435,issued to A. Greene et al., on Dec. 23, 1969 wherein the panels 50 and52 along with the panels 32 and 34 were folded about the scorelines 38and 48 to form the end cell structure shown in FIG. 4 of the drawing.

While all of the beforementioned prior art end cell constructionsprovided some cushioning effect to the article being packaged, for onereason or another they have not found wide acceptance in the marketplaceundoubtedly due to either the amount of protection that they provided,the cost of obtaining the protection by means of a larger productionblank or the problems of machining the production blank which is theterm referred to in the art to mean the machine folding of theproduction blank around the article packaged in the container. Asomewhat more up-to-date end cell structure is shown in the U.S. Pat.No. 3,664,573, issued to J. H. Partain et al. on May 23, 1972 whereinthe end cell is formed with a four panel effect with the cellarrangement, shown as the numeral 30, forming actually two panels of thefour panel end cell. As can be seen in FIG. 3 of his drawing the endcell construction of this invention utilizes an upwardly and outwardlyinclined panels formed out of panels 42 in combination with a pluralityof horizontal panels formed out of panels 40, both of these panels beingshown generally by the numeral 30 in the drawing. In combination withthis there is provided a vertical panel 56 and a horizontal panel 54which is wedged between the book and the second rectangular panel 14 asshown in FIG. 6 of the drawing. A more complicated version of thispatent is shown in the U.S. Pat. No. 3,666,168, issued to J. H. Partainet al., on May 30, 1972. While these structures may provide the desiredcushioning of the book with their particular end cell structures, it isfelt that whenever the particular production blank is machined, or asbefore mentioned, folded around the book to be contained in the package,problems will occur which will make the use of this containereconomically prohibitive.

In the packing of books into containers such as taught by the inventionand the prior art cited herein, it is well known that assembly linespeeds ranging between 20 and 40 books per minute are commonplace withthe books being generally positioned in the package manually by womenpackers who build up quite a manual dexterity in placing the books inthe package while the packaging line is traveling at the high rate ofspeed necessary to handle the 20 to 40 books per minute. In machiningthe mailing container taught by the first mentioned Partain patent, itbecomes necessary to first fold the cell construction 30 in the mannershown in FIG. 3 of the drawing and then to fold down the wall panel 56and to fold overthe wall panel 54 while holding it in position so thatthe book can be rapidly placed in the container. While this folding canbe accomplished automatically by the packaging machine it is felt thatsuch a machine would be expensive to manufacture and would beexceedingly large in order to handle all of the folding steps necessaryprior to the place ment of the book in the container. If some of thefolding steps are performed manually, as for example breaking thescoreline 58 in order to fold the wall panel 54 horizontally and to holdit in place while the book is placed in the package, then it isquestioned whether or not the before mentioned packaging speeds would beobtainable using this structure. My copending appli-' cations, entitledShipping Container, Ser. Nos. 290,724 and 290,725 filed Sept. 20, 1972,disclose structures which are designed to solve these problems.

SUMMARY OF THE INVENTION Another design to overcome the problemsinherent in the prior art patents is provided by the subject invention.It includes new and improved shipping container for a book or the likewhich has a new and novel end cell construction which may be easilyformed into the cushioning end cell thereby allowing the high packagingline speeds to be accomplished in the packaging process. In thepreferred embodiment shown the cushioning end cell may be formed withthree cushioning panels which are attached to each other and to thebottom panel and are foldable along score lines to form a rectangular orsquare cellular structure. Reinforcement panels are formed in two of thethree cushioning panels of the structure and are adapted to foldinwardly so as to rigidify and maintain the cellular position of thecushion panels. The reinforcement panels may be formed in the shape of atriangle from each of two cushion panels, the two triangles having acommon leg with each other and with its associated cushion panel, butsevered therefrom along a third leg.

Accordingly it is an object of the invention to provide a new andimproved shipping container that may be easily machined at the highpackaging speeds required in todays technology.

Still another object of the invention is to provide a new and improvedshipping container which has an end cell construction that providesimproved cushioning of the contents of the package without requiringlarge amounts of paperboard for the construction blank or withoutrequiring intricate and large numbers of folding panels in order toprovide the end cell cushioning.

Still another object and advantage of the invention is to provide animproved mailing container which utilizes end cell cushioning providedby three cushioning panels, two of which have formed thereon cushioningreinforcement panels.

These and other objects and advantages of the invention will becomeapparent from a reading of the description of the preferred embodimentand from a study of the drawings showing the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of theproduction blank of the subject invention;

FIG. 2 is a perspective view showing the blank of FIG. 1 with the leftend cell partially folded and the right end cell completely folded inplace prior to the top panel being folded over to make the completedpackage;

FIG. 3 is a partial top view taken along line 3-3 of FIG. 2 showing thenew and improved end cell construction;

FIG. 4 is an end view taken along line 44 of FIG. 2 showing the end cellconstruction as assembled but prior to the top panel being completelyfolded over to complete the package;

FIG. 5 is an end view taken along line 5-5 of FIG. 3 showing the endcell construction of the invention after the top panel has been foldedin place but before the cover panel has been folded in place completingthe package; and

FIG. 6 is a bottom view of the completed package showing the three coverpanels folded in place and showing the end cell construction in dashedlines on the Figure.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings ingeneral and in particular to FIG. 1 of the drawings there is shown thenew and novel shipping container of the invention generally by thenumeral 10 which comprises a top panel 12 and a bottom panel 14 which ishingedly attached to the top panel 12 by means of an end panel 16 at thescorelines l8 and 20. The top panel 12 also has hingedly attachedthereto, by means of the scorelines 22, 24 and 26, the

end panels 28, 30 and 32. Hingedly attached to the end panels 28, 30 and32, by means of the scorelines 34, 36 and 38 are a plurality of coverpanels 40, 42 and 44.

The bottom panel 14 has hingedly attached thereto, on each of twoopposite sides thereof, a plurality of cushioning panels 46, 48, 50, 52,54 and 56 by means of a slit scorelines 58, 60, 62, 64, 66 and 68. Asshown in FIG. 2, these cushioning panels are foldable at right angles tothe bottom panel 14 and to each other to form a square or rectangularcushion cell at opposite ends of the box. To provide rigidity to thesecells. reinforce ment panels (shown generally at numeral 70) are formedin the cushion panels. These reinforcement panels generally take theshape of pairs of triangles 72, 74, 76 and 78 and conjointly define atrapezoid. Thus, cutlines 108 along the edge of bottom panel 14 defineone leg of triangles 74 and 78 while a cutline 110 defines a leg oftriangles 72 and 76, these two cutlines being perpendicular to oneanother. Slit scorelines define a second common leg of each pair oftriangles 72, 74 and 76, 78, these scorelines being at a 45 degree angleto each of the cutlines and 108. Finally, slit scorelines 96 and 98 formthe remaining legs of the triangles and permit them to be flexedinwardly from their associated cushion panels to form the reinforcingstructure. To facilitate folding of the panels 70, additional materialmay be cut away from the legs of the triangles 74 and 78 adjacent cutline 108 as indicated in FIG. 1. Such may cause the triangular panels 72and 76 to take a trapezoid appearance having a very short leg adjacentcut line 108.

Referring now to FIG. 2 of the drawing there is shown a perspective viewof the production blank of FIG. 1 with the left end cell being partiallyfolded and the right end cell being completely folded and with thereinforcement panels 70 structurally reinforcing the cushioning panelsin order to provide cushioning support to the book or other objectplaced within the container. When the cushioning end panels areinitially formed as shown on the left side of FIG. 2 of the drawing, abreaking force is applied from beneath the reinforcement panels 70 whenthey are in the unfolded position shown in FIG. 1 of the drawing inorder that the cushioning panels may be wrapped around the inwardlyopening reinforcement panels as the cushioning panel is formed. Whencompletely formed, the cushioning panel 46 is in juxtaposition with thebottom panel 14 along the line 116 as shown by the dotted line 117representing its final position and the cushioning panel 56 is injuxtaposition with the bottom panel 14 along the line 118, both beingsubstantially vertical in relation to the bottom panel 14. When formedin this manner the cushioning panels 48 and 54 are thensubstantially-horizontal in relation to the bottom panel 14 and thecushioning panels 50 and 52 are substantially vertical in relaiton tothe bottom panel 14 and lie on the outside of the package. Uponassembly, the reinforcement panels 70 provide a Vshaped opening, 119 and120 (see FIG. 3) on each side of the package with the triangular-shapedpanels 72, 74, 76 and 78, giving structural support to the cushioningpanels 46 and 56. However, as opposed to the invention of my copendingapplications, the bottom panel 14 remains rectangular and the V-shapednotch does not extend into this panel. Thus, the two triangular panels,72 and 74, each attached along one leg to cushion panels 48 and 50 andjoined along a common leg (slit scorelines 100) urge another leg 110a(formed by cut line 1 into abutting and supporting engagement withcushion panels 46 and 56. The other pair of panels 76 and 78 providesimilar support to these panels. Too, the severed legs of triangles 74and 78 may engage the bottom panel.

Referring now to FIG. 3 of the drawing there is shown apartial top viewtaken along lines 33 of FIG. 2 showing the improved end cellconstruction folded in place as beforementioned prior to the top panel12 being folded over the end cells to make the complete package.Whenever a book 122 or other similar object is placed within the packageand the package is completely made up, the longitudinal forces. shown bythe arrow direction 124, will be cushioned by the end cell. The shock isinitially absorbed by the cushioning panels 46 and 56. However, it isalso absorbed by the cushioning panels 50 and 52 by virtue of theresultant force being transferred to these latter panels by means of thereinforcement panels 70 being folded in the particular manner taught bythe subject invention. Referring to FIG. 4 of the drawing there is shownan end view taken along line 4-4 of FIG. 2 showing the end cellconstruction prior to the top panel being completely folded over tocomplete the package and showing the book 122 in place in the package.In addition to the forces 124 occurring to cause potential damage to thebook 122 there may also be a plurality of diagonal forces applied to theedges of the book as shown by the arrow direction 126. Due to the uniqueconstruction of the end cell, a hollow space 128 is provided which issufficient to allow the cushioning panel 46 or 56 to deflect inward orto somewhat collapse in order to absorb the shock incurred by means ofthe force applied to the diagonal corners of the book as shown by thearrow direction 126. Referring now to FIG. 5 of the drawing there isshown an end view taken along line 5--5 of FIG. 3

showing the end cell construction of the invention after the top panelhas been folded in place but before the cover panel has been folded inplace to complete the package. As beforementioned the reinforcementpanels 70 are formed by means of the triangular-shaped pairs of panelswhich jointly take the general form of a trapezoid. In the view shown inFIG. 5, the base or leg 110a of triangles 72 and 76 are held in abuttingrelation to its associated cushion panel 46 and 56 by the triangles andtheir interconnection to each other and to the cushion panels 48, 50, 52and 54.

Referring to FIG. 6 of the drawing there is shown a bottom view of thecompleted package. showing the three cover panels folded in place andshowing the end cell construction with a plurality of dashed lines onthe figure.

The coverpanel 42 as well as the cover panels and 44 are generallyformed with tapered sides at 140 and 144 as well as 142 and 146 in orderthat the threecover panels can be tightly folded in place and gluedtoform the completed package by means well known in the art.

When the completed package is thusly formed, the out- I sively attachedto the bottom surface of bottom panel 14.

From the above it should become apparent that there has been provided bythe subject invention. a new and improved shipping container for a bookor the like having an improved cushioning end cell structure which maybe simply formed out of a minimum of panels and which provides therequired structural support to the book contained within the packagewhenever various shocking forces are applied to the edges of the booksresulting from the improper handling of the package. When the subjectimproved package is to be machined, a simple breaking force is requiredto the reinforcement panels to break them upwardly and the end cell canthen be quickly formed by wrapping the cushioning panels around thereinforcement panels with the book being placed in the package withoutrecourse being made to other means to hold the end cell in a properposition prior to insertion of the book. As a result the beforementionedhigh packaging speeds are obtainable with the unique end cellconstruction of the invention thereby overcoming the problems inherentin the beforementioned prior art book packages.

From the above it should become apparent that many variations may beutilized within the spirit and scope of the invention in order to takeadvantage of the unique end cell construction. For example, in thepreferred embodiment shown, the reinforcement structure comprises twotrapezoicls in each cushion cell, each formed of two triangles. It isalso conceivable that the structure could be formed with only one ormore than two trapezoids on each side of the package.

From the foregoing it can be seen that there has been provided a new andimproved shipping package which accomplishes all of the objects andadvantages of the invention as outlined before. Nevertheless, manychanges may be made in the basic structure of the invention and in thearrangement of the panels without departing from the spirit and scope ofthe invention and the invention is not to be limited to the preferred embodiment shown which has been given by way of illustration only.

Having described my invention, I claim:

1. In a box blank foldable into a shipping container for a book or thelike and having top and bottom panels hingedly connected by a sidepanel, the improvement comprising: r

a. three cushion panels pivotally connected to the bottom panel andfoldable into a hollow rectangular cellular cushion on at least one sideof the bottom panel;

b. a reinforcing means formed from said box blank and foldableinwardlytoe'xtend between the interior surfaces of said cellular cushionfor supporting said cushion against collapse.

2. A device as recited in claim 1 in which said reinforcing meanscomprises two triangular shaped panels each joined along one leg to thebox blank and to each other along a second leg while a third leg engagesand abuts an adjacent interior surface for supporting same.

3. A device as recited in claim 2 in which said triangular panels areformed by cut lines and score line in the two cushion panels adjacentsaid bottom panel.

4. A device as recited in claim 3 in which two reinforcing means areprovided for said cellular cushion.

5. A device as recited in claim 2 in which one of said triangular panelsis formed from two cushion panels and the other is formed solely fromone cushion panel.

'6. ln ashipping container for a book or the like and of the typecomprising a top panel, a plurality of end panels hingedly attached tothe top panel, a plurality of cover panels hingedly attached to at leastthree of the end panels and a bottom panel hingedly attached to at leastone of the end panels, the improvement comprismg:

a. at least two cushioning panels pivotally extending from each of twoopposite sides of the bottom panel, one of said cushioning panels oneach side positioned at about a 90 angle to the bottom panel and theother cushioning panel of each side positioned substantially parallel tothe bottom panel to form an end cell structure;

b. triangular tab portions formed from said cushioning panels andextending inwardly of said end cell structure, said tab portions beingjoined together along a common leg of each tab portion, having anotherleg of each tab portion pivotally attached to the panel from which it isformed, and another leg in supporting position to an article within saidcontainer.

7. An apparatus as recited in claim 6 in which the end cell structureincludes:

a. a third cushioning panel pivotally extending from said other two endpanels and positioned at about a 90 angle to said bottom panel to form arectangular end cell structure with said other cushion panels and saidbottom panel.

8. In a container blank foldable into a box like structure for shippingarticles, an improved cushioning structure comprising:

a. panels extending from at least one of the sides of said blank andfoldable to form a rectangular protective end cell, said end cell havingtwo triangular sections extending inwardly from at least two of saidpanels along one leg, said triangular sections being joined to eachother along a common leg of each section and severed from the blankalong the other leg.

9. A device as recited in claim 8 in which the severed leg of onesection is in abutting relation to an adjacent panel to providereinforcement to said end cell.

10. A device as recited in claim 8 in which said triangular sectionscomprise a trapezoid having a diagonal score line.

11. A device as recited in claim 8 in which each section issubstantially an isosceles triangle.

12. A device as recited in claim 8 in which additional material issevered from each leg to facilitate inward folding of said triangles.

13. In a shipping container having a pair of protective end cells for abook or the like and of the type comprising a top panel, a plurality ofend panels hingedly attached to the top panel, a plurality of coverpanels hingedly attached to at least three of the end panels and abottom panel hingedly attached to at least one of the end panels, theimprovement comprising:

a. a first cushioning panel formed on each of two opposite sides of thebottom panel and extending at about a 90 angle to said bottom panel, asecond cushioning panel attached to the first cushioning panel at abouta 90 angle, and a third cushioning panel attached to the secondcushioning panel at about a 90 angle to form a rectangular protectiveend cell; and b. a triangular tab portion extending inwardly of saidrectangular end cell from each of said first and second cushioningpanels, said portions being joined along a common leg of each triangularportion and having a second leg in abutting relation to adjacentsurfaces of said end cell.

14. A device as recited in claim 13 in which each end cell is providedwith two triangular tab portions.

l l =l 22x2?" UNITED, STATES CERTIFICATE OF (g-ORRECTION 2 PatentNo3,820,709 Dgtgd June 28, 1974 nmfl William G suffer-1;

It is certified that error appears it; the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 1, line 53, after "Greene at al omit Column 2, "line 17, after"J; H. Partain et a1" omit Column 8, .line 31, after "and" make newsub-paragraph b.--.

Signed "and sealed this 5th day of November 1974.

Attest:

McCOY M. GIBSON JR. c. MARSHAL DANN Attesting Officer Commiesioner ofpatents

1. In a box blank foldable into a shipping container for a book or thelike and having top and bottom panels hingedly connected by a sidepanel, the improvement comprising: a. three cushion panels pivotallyconnected to the bottom panel and foldable into a hollow rectangularcellular cushion on at least one side of the bottom panel; b. areinforcing means formed from said box blank and foldable inwardly toextend between the interior surfaces of said cellular cushion forsupporting said cushion against collapse.
 2. A device as recited inclaim 1 in which said reinforcing means comprises two triangular shapedpanels each joined along one leg to the box blank and to each otheralong a second leg while a third leg engages and abuts an adjacentinterior surface for supporting same.
 3. A device as recited in claim 2in which said triangular panels are formed by cut lines and score linein the two cushion panels adjacent said bottom panel.
 4. A device asrecited in claim 3 in which two reinforcing means are provided for saidcellular cushion.
 5. A device as recited in claim 2 in which one of saidtriangular panels is formed from two cushion panels and the other isformed solely from one cushion panel.
 6. In a shipping container for abook or the like and of the type comprising a top panel, a plurality ofend panels hingedly attached to the top panel, a plurality of coverpanels hingedly attached to at least three of the end panels and abottom panel hingedly attached to at least one of the end panels, theimprovement comprising: a. at least two cushioning panels pivotallyextending from each of two opposite sides of the bottom panel, one ofsaid cushioning panels on each side positioned at about a 90* angle tothe bottom panel and the other cushioning panel of each side positionedsubstantially parallel to the bottom panel to form an end cellstructure; b. triangular tab portions formed from said cushioning panelsand extending inwardly of said end cell structure, said tab portionsbeing joined together along a common leg of each tab portion, havinganother leg of each tab portion pivotally attached to the panel fromwhich it is formed, and another leg in supporting position to an articlewithin said container.
 7. An apparatus as recited in claim 6 in whichthe end cell structure includes: a. a third cushioning panel pivotallyextending from said other two end panels and positioned at about a 90*angle to said bottom panel to form a rectangular end cell structure withsaid other cushion panels and said bottom panel.
 8. In a container blankfoldable into a box like structure for shipping articles, an improvedcushioning structure comprising: a. panels extending from at least oneof the sides of said blank and foldable to form a rectangular protectiveend cell, said end cell having two triangular sections extendinginwardly from at least two of said panels along one leg, said triangularsections being joined to each other along a common leg of each sectionand severed from the blank along the other leg.
 9. A device as recitedin claim 8 in which the severed leg of one section is in abuttingrelation to an adjacent panel to provide reinforcement to said end cell.10. A device as recited in claim 8 in which said triangular sectionscomprise a trapezoid having a diagonal score line.
 11. A device asrecited in claim 8 in which each section is substantially an isoscelestriangle.
 12. A device as recited in claim 8 in which additionalmaterial iS severed from each leg to facilitate inward folding of saidtriangles.
 13. In a shipping container having a pair of protective endcells for a book or the like and of the type comprising a top panel, aplurality of end panels hingedly attached to the top panel, a pluralityof cover panels hingedly attached to at least three of the end panelsand a bottom panel hingedly attached to at least one of the end panels,the improvement comprising: a. a first cushioning panel formed on eachof two opposite sides of the bottom panel and extending at about a 90*angle to said bottom panel, a second cushioning panel attached to thefirst cushioning panel at about a 90* angle, and a third cushioningpanel attached to the second cushioning panel at about a 90* angle toform a rectangular protective end cell; and b. a triangular tab portionextending inwardly of said rectangular end cell from each of said firstand second cushioning panels, said portions being joined along a commonleg of each triangular portion and having a second leg in abuttingrelation to adjacent surfaces of said end cell.
 14. A device as recitedin claim 13 in which each end cell is provided with two triangular tabportions.